Distilled water is a type of purified water that has been heated and then cooled back into its liquid form. The process involves boiling water, which causes it to evaporate, leaving behind impurities such as minerals and salts. The vapor is then condensed back into liquid form through a cooling system, resulting in pure H2O that has been stripped of any unwanted substances. This method ensures that the water is free from contaminants and meets high standards for purity.